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Slotting Machine.                             17 3

obtained by means of the worm spindle /, provided with a handle,
and worm gearing into the segment f, which is pivoted at 3. We
may thus shape a corner or give a feed (by hand) for a concave
surface. The front of tool box is provided with the usual flap to
relieve the tool during the return stroke, and the tool itself takes
the same shape as that described for the planing machine.

The Slotting Machine is probably the least economical
of machine tools. While the planing machine takes simple
horizontal cuts, and the shaping machine tools cylindrical work
lying horizontally, the slotting machine is for the production of
vertical cylindrical and plane services. Though working at a
disadvantage in having to lift a heavy ram, this machine has
served a purpose, and is still used to a large extent. Smaller
work can generally be accommodated in a shaping machine, but
the slotting machine is used for heavier work, and is made more
powerful.

Plate XI. "represents one of these machines, as made by Sir
J. Whitworth & Co. Power being given to the cone A, it may be
passed directly to the mandrel B, or through the back gear at c,
the back shaft being moved to the left or right, or (Fig. 175) to
put the wheels in or out of gear respectively. The power is further
taken from the mandrel to the ram through the medium of a quick
return motion. Looking at the front of the ram, and keeping our
attention on both views, the spur wheel E is driven by the pinion
F, and the motion transmitted to the crank disc G by pin H. The
spur wheel turns on the boss j, and the crank disc in K, their
centres being i| inches apart horizontally. Referring to Fig. 177,
if the spur wheel rotate uniformly it will pass through 10 divisions
while bringing the pin from H to Hly but through only 7 divisions
from H! to H, and the advance will bear the proportion of 10 to
the return 7. As some sliding takes place between pin H and
disc o, a die is provided. The rod L connects the crank disc
with the rarn M, and there are two adjustments; one at N to fix
the height of the ram; the other at p, where the rotation of two
screws is made to move the pin and regulate the throw of the
crank. A brake block Q, bearing on the crank disc, may be
tightened by screwing up the wedge R, and serves to fix the ram
in positions where it might fall on account of its weight

There are three feed motions, all taken from cam s, the